Trouble automounting an SD card on Trusty

Question

I need an SD card to be mounted unattended, as soon as it is inserted in its slot. Usual enough, but the prbm is it does not get mounted and I am missing why.

In /etc/fstab:

#Entry for /dev/mmcblk0p1 :
UUID=_____   /mnt/SD-root ext3 defaults,nofail,umask=0027,utf8,comment=x-gvfs-show,x-gvfs-name=SD-root 0 2

EDIT-1: I also tried replacing /mnt/ with /media/myname/ above, and including the options user,uid=1000 (that's me) or users, to no avail.

Mount point is either /mnt/SD-root or /media/myname/SD-root. Mountpoint ownership is set to "root : adm".

$ ls -Al /mnt/ | grep -e 'SD-root'
1 drwxr-x--- 3 root adm 1024 Sep 25 16:51 SD-root/

Right now the only way for a non-root user to mount the SD card is to:

$  sudo mount /dev/mmcblk0p1 /mnt/SD-root/

What am I missing ?

/etc/fstab is for automounting when you boot not for automounting when you insert the card — mchid, Sep 29 '15 at 03:58
@Mchid: Not precisely. /etc/fstab is read at boot time when mountall is invoked to mount filesystems and detected block-devices are listed and don't have option noauto set . However /etc/fstab can also be and is used to list mounting options for devices not meant to be mounted at boot. Isn't that's the raison d'être of the option noauto ? — Cbhihe, Sep 29 '15 at 15:10
It doesn't work because: /etc/fstab is for automounting when you boot not for automounting when you insert the card — mchid, Sep 29 '15 at 20:38

A.B. · Accepted Answer · 2015-10-26T18:19:29.570

3

To mount the card automatically at /mnt in a running system you could use an additional udev rule. Without the rule, the card is mounted in /media/$USER/… and /dev/disk/….

The following script and udev rule create a folder in /mnt and mount a the partition with a defined UUID. In the current version, the mountpoint is the label of the mounted partition. I personally think, that's a bad idea. I would prefer the UUID and not the label, but the OP wanted this solution.

The script

Create a script in /usr/local/bin
```
sudo nano /usr/local/bin/mount_by
```

Add the code below

#!/bin/sh
export mount_point="/mnt/$1"
existing_device=$(awk '$2 == ENVIRON["mount_point"] {print $1; exit}' < /proc/mounts)
if [ -n "$existing_device" ]; then
  exit 1
fi
mkdir -p "$mount_point"
sleep 1 # Perhaps not necessary, but in the test with the OP it was necessary
mount "/dev/disk/by-uuid/$2" "$mount_point"
exit 0

Make the script executable
```
sudo chmod +x /usr/local/bin/mount_by
```

The udev rule

Create a new rule

sudo nano /etc/udev/rules.d/99-myrules.rules

Add the code below

ENV{ID_FS_UUID}=="c8bf306d-3d5d-4878-8045-e4087494eff0", RUN+="/usr/local/bin/mount_by '%E{ID_PART_ENTRY_NAME}' '%E{ID_FS_UUID}'"

or if your drive hasn't the ID_PART_ENTRY_NAME, try ID_FS_LABEL

Suppose that the partition is /dev/sdc1 Replace the value for ENV{ID_FS_UUID}== above with the output of
```
udevadm info /dev/sdc1 | awk -F= '/ID_FS_UUID=/ {print $2}'
```

Restart udev
```
sudo service udev restart
```

Plugin your SD card and you should see something like this

% ls -la /mnt
total 12
drwxr-xr-x  3 root root 4096 Okt  6 19:29 .
drwxr-xr-x 25 root root 4096 Sep 29 17:04 ..
drwxr-xr-x  4 root root 4096 Okt  6 19:31 Label1

edited Oct 26 '15 at 18:19

answered Sep 29 '15 at 13:34

A.B.

90,397

Can you give me pointers to a wiki or else to learn about udev rules ? – Cbhihe Sep 29 '15 at 16:06
@Cbhihe: "Yes, expand your answer" = "I'll click ☑" (which means Yes, this answer is valid) so you can expand the answer... – Fabby Sep 29 '15 at 17:52
@Fabby: Gee ! I was waiting for you to answer, just so I could select his ! Bear with me until tomorrow. Till then my hands are full. – Cbhihe Sep 29 '15 at 19:16
1

@Cbhihe: I'm not A.B. ... Just dropping by because I didn't see an accepted answer! ;-) – Fabby Sep 29 '15 at 19:58
I can't read your dropbox. Please use http://paste.ubuntu.com/ – A.B. Oct 01 '15 at 06:00
Please check the new part in my answer. Check the difference here http://askubuntu.com/posts/679669/revisions – A.B. Oct 06 '15 at 17:19
Ok, test it again. I have changed the script and the rule a little bit. Works for me. – A.B. Oct 06 '15 at 17:32
And you need the export mount_point="/mnt/$1" to use it in the awk script or use awk -v …. – A.B. Oct 06 '15 at 17:40
@A.B. I found the tiny problem that remained ! The udev rule initial match on the event dev tag KERNEL=="s???" is wrong. It should be KERNEL=="mm*" when dealing with an mmcblk type SD card. --- Can you just modify your udev rule so I can mark yr answer as correct ? Thank you for your help A.B. I appreciate yr time and explanation. – Cbhihe Oct 07 '15 at 19:12
Great :) Now I'm happy. Maybe it's better without the KERNEL... parameter. Delete the thing and try it again. – A.B. Oct 07 '15 at 19:25
I have changed my answer. And if it's correct, don't forget to accept my answer :) – A.B. Oct 07 '15 at 19:27
.. and don't forget to add the sleep 1 before the mkdir -p ... in yr answer. Without that the script breaks. Tx. – Cbhihe Oct 08 '15 at 08:31

score 1 · Answer 2 · answered Oct 26 '15 at 22:49

I setup fresh new Ubuntu 14.04 to test this. The SD card formated as EXT3. The is automounted.

Here output of mount with different setups

With default setup, no fstab entry:

/dev/mmcblk0p1 on /media/sneetsher/test0 type ext3 (rw,nosuid,nodev,uhelper=udisks2)

With fstab:

/dev/mmcblk0p1                            /media/test0    ext3    nodev,noexec,comment=x-gvfs-show 0       0

mounted as:

/dev/mmcblk0p1 on /media/test0 type ext3 (rw,noexec,nodev)

With fstab:

/dev/mmcblk0p1                            /media/test0    ext3    defaults,nofail,umask=0027,utf8,comment=x-gvfs-show,x-gvfs-name=SD-root 0 2

Found dmesg errors:

[ 3339.729139] EXT4-fs (mmcblk0p1): Unrecognized mount option "umask=0027" or missing value

removed, then found:

[ 3410.950108] EXT4-fs (mmcblk0p1): Unrecognized mount option "utf8" or missing value

removed, then found:

[ 3490.129696] EXT4-fs (mmcblk0p1): Unrecognized mount option "x-gvfs-name=SD-root" or missing value

changed to:

/dev/mmcblk0p1                            /media/test0    ext3    defaults,nofail,comment=x-gvfs-show,comment=x-gvfs-name=SD-root 0 2

mounted as:

/dev/mmcblk0p1 on /media/test0 type ext3 (rw,_netdev)

x-gvfs-name is effective as it shown as SD-root in nautilus.

Did I miss some thing from your setup?

Thanks for taking the time Sneetsher. As evidenced by yr tests utf8 is not a valid option for ext4 or ext3. Also the umask=---- options spells trouble. That I don't comprehend. Nevertheless at least for the time being, my preferred mount route is that proposed by @A.B., i.e. with udev rules. — Cbhihe, Oct 27 '15 at 08:04
Could you reference from where did you get those options, I could find them in man mount for some other file systems but not for ext3. — user.dz, Oct 27 '15 at 18:35

score 0 · Answer 3 · answered Apr 04 '16 at 18:49

0

Just take the ownership of the folder /media/test0.

chown user.user /media/test0

answered Apr 04 '16 at 18:49

user526624

1

Trouble automounting an SD card on Trusty

3 Answers3

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